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llvm-mirror/test/Transforms/InstCombine/sink_to_unreachable.ll
Max Kazantsev 23bde48f84 [InstCombine] Sink pure instructions down to return and unreachable blocks
If the only user of `Instr` is in a return or unreachable block, we can
sink `Instr` to the`User` safely (unless it reads/writes memory).
Return or unreachable blocks are guaranteed to execute zero
or one time, and `Instr` always dominates `User`, so they either will
be executed together (execution of `User` always implies execution
of `Instr`) or not executed at all.

Differential Revision: https://reviews.llvm.org/D80120
Reviewed By: asbirlea, jdoerfert
2020-05-22 14:33:42 +07:00

161 lines
4.4 KiB
LLVM

; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
; RUN: opt -instcombine -S < %s | FileCheck %s
; RUN: opt -passes=instcombine -S < %s | FileCheck %s
declare void @use(i32 %x)
declare i1 @cond()
define void @test_01(i32 %x, i32 %y) {
; CHECK-LABEL: @test_01(
; CHECK-NEXT: entry:
; CHECK-NEXT: [[C2:%.*]] = icmp slt i32 [[X:%.*]], [[Y:%.*]]
; CHECK-NEXT: br i1 [[C2]], label [[EXIT:%.*]], label [[UNREACHED:%.*]]
; CHECK: unreached:
; CHECK-NEXT: [[C1:%.*]] = icmp ne i32 [[X]], [[Y]]
; CHECK-NEXT: [[COMPARATOR:%.*]] = zext i1 [[C1]] to i32
; CHECK-NEXT: call void @use(i32 [[COMPARATOR]])
; CHECK-NEXT: unreachable
; CHECK: exit:
; CHECK-NEXT: ret void
;
entry:
%c1 = icmp eq i32 %x, %y
%c2 = icmp slt i32 %x, %y
%signed = select i1 %c2, i32 -1, i32 1
%comparator = select i1 %c1, i32 0, i32 %signed
br i1 %c2, label %exit, label %unreached
unreached:
call void @use(i32 %comparator)
unreachable
exit:
ret void
}
define void @test_02(i32 %x, i32 %y) {
; CHECK-LABEL: @test_02(
; CHECK-NEXT: entry:
; CHECK-NEXT: [[C2:%.*]] = icmp slt i32 [[X:%.*]], [[Y:%.*]]
; CHECK-NEXT: br i1 [[C2]], label [[EXIT:%.*]], label [[MEDIUM:%.*]]
; CHECK: medium:
; CHECK-NEXT: [[C3:%.*]] = icmp sgt i32 [[X]], [[Y]]
; CHECK-NEXT: br i1 [[C3]], label [[EXIT]], label [[UNREACHED:%.*]]
; CHECK: unreached:
; CHECK-NEXT: [[C1:%.*]] = icmp eq i32 [[X]], [[Y]]
; CHECK-NEXT: [[SIGNED:%.*]] = select i1 [[C2]], i32 -1, i32 1
; CHECK-NEXT: [[COMPARATOR:%.*]] = select i1 [[C1]], i32 0, i32 [[SIGNED]]
; CHECK-NEXT: call void @use(i32 [[COMPARATOR]])
; CHECK-NEXT: unreachable
; CHECK: exit:
; CHECK-NEXT: ret void
;
entry:
%c1 = icmp eq i32 %x, %y
%c2 = icmp slt i32 %x, %y
%signed = select i1 %c2, i32 -1, i32 1
%comparator = select i1 %c1, i32 0, i32 %signed
br i1 %c2, label %exit, label %medium
medium:
%c3 = icmp sgt i32 %x, %y
br i1 %c3, label %exit, label %unreached
unreached:
call void @use(i32 %comparator)
unreachable
exit:
ret void
}
define i32 @test_03(i32 %x, i32 %y) {
; CHECK-LABEL: @test_03(
; CHECK-NEXT: entry:
; CHECK-NEXT: [[C2:%.*]] = icmp slt i32 [[X:%.*]], [[Y:%.*]]
; CHECK-NEXT: br i1 [[C2]], label [[EXIT:%.*]], label [[MEDIUM:%.*]]
; CHECK: medium:
; CHECK-NEXT: [[C3:%.*]] = icmp sgt i32 [[X]], [[Y]]
; CHECK-NEXT: br i1 [[C3]], label [[EXIT]], label [[UNREACHED:%.*]]
; CHECK: unreached:
; CHECK-NEXT: [[C1:%.*]] = icmp eq i32 [[X]], [[Y]]
; CHECK-NEXT: [[SIGNED:%.*]] = select i1 [[C2]], i32 -1, i32 1
; CHECK-NEXT: [[COMPARATOR:%.*]] = select i1 [[C1]], i32 0, i32 [[SIGNED]]
; CHECK-NEXT: ret i32 [[COMPARATOR]]
; CHECK: exit:
; CHECK-NEXT: ret i32 0
;
entry:
%c1 = icmp eq i32 %x, %y
%c2 = icmp slt i32 %x, %y
%signed = select i1 %c2, i32 -1, i32 1
%comparator = select i1 %c1, i32 0, i32 %signed
br i1 %c2, label %exit, label %medium
medium:
%c3 = icmp sgt i32 %x, %y
br i1 %c3, label %exit, label %unreached
unreached:
ret i32 %comparator
exit:
ret i32 0
}
define i32 @test_04(i32 %x, i1 %c) {
; CHECK-LABEL: @test_04(
; CHECK-NEXT: bb0:
; CHECK-NEXT: br i1 [[C:%.*]], label [[BB1:%.*]], label [[BB2:%.*]]
; CHECK: bb1:
; CHECK-NEXT: br label [[BB3:%.*]]
; CHECK: bb2:
; CHECK-NEXT: br label [[BB3]]
; CHECK: bb3:
; CHECK-NEXT: [[P:%.*]] = phi i32 [ 0, [[BB1]] ], [ 1, [[BB2]] ]
; CHECK-NEXT: [[A:%.*]] = add i32 [[X:%.*]], 1
; CHECK-NEXT: [[R:%.*]] = add i32 [[P]], [[A]]
; CHECK-NEXT: ret i32 [[R]]
;
bb0:
%a = add i32 %x, 1
br i1 %c, label %bb1, label %bb2
bb1:
br label %bb3
bb2:
br label %bb3
bb3:
%p = phi i32 [0, %bb1], [1, %bb2]
%r = add i32 %p, %a
ret i32 %r
}
; Do not sink into a potentially hotter block.
define i32 @test_05_neg(i32 %x, i1 %cond) {
; CHECK-LABEL: @test_05_neg(
; CHECK-NEXT: bb0:
; CHECK-NEXT: [[A:%.*]] = add i32 [[X:%.*]], 1
; CHECK-NEXT: br i1 [[COND:%.*]], label [[BB1:%.*]], label [[BB2:%.*]]
; CHECK: bb1:
; CHECK-NEXT: br label [[BB3:%.*]]
; CHECK: bb2:
; CHECK-NEXT: [[CALL:%.*]] = call i1 @cond()
; CHECK-NEXT: br i1 [[CALL]], label [[BB2]], label [[BB3]]
; CHECK: bb3:
; CHECK-NEXT: [[P:%.*]] = phi i32 [ 0, [[BB1]] ], [ [[A]], [[BB2]] ]
; CHECK-NEXT: ret i32 [[P]]
;
bb0:
%a = add i32 %x, 1
br i1 %cond, label %bb1, label %bb2
bb1:
br label %bb3
bb2:
%call = call i1 @cond()
br i1 %call, label %bb2, label %bb3
bb3:
%p = phi i32 [0, %bb1], [%a, %bb2]
ret i32 %p
}